Discharge scroll and turbomachine

ABSTRACT

Provided is an exhaust scroll capable of reducing mixing loss caused by fluid swirling inside the exhaust scroll and fluid flowing thereinto, while collecting and discharging the fluid which has flowed. The exhaust scroll is provided with a scroll body ( 11 ) in which a space having a substantially annular cross section is formed and a connecting portion ( 12 ) which connects an exhaust passage ( 8 ) with the scroll body ( 11 ) to forcibly decelerate fluid (A) discharged from the exhaust passage ( 8 ), thereby allowing the fluid (A) to flow into the scroll body ( 11 ).

TECHNICAL FIELD

The present invention relates to an exhaust scroll connected to an exhaust passage of a turbomachinery and a turbomachinery having the same.

Priority is claimed on Japanese Patent Application No. 2009-214814, filed Sep. 16, 2009, the content of which is incorporated herein by reference.

BACKGROUND ART

A turbomachinery such as a compressor, a turbine and a pump is mounted with an exhaust scroll formed in an annular shape on an exhaust passage of working fluid. The working fluid is collected inside the exhaust scroll to flow as fluid swirling along the circumferential direction and discharged from an exhaust pipe extended to the side of the outer circumference in the radial direction (for example, refer to Patent Documents 1, and 2).

FIG. 8 is a drawing which shows a conventional exhaust scroll mounted on an exhaust passage of an axial-flow compressor. As shown in FIG. 8, the axial-flow compressor is provided with a diffuser 100 formed so as to have a substantially annular cross section as an exhaust passage at the end of a passage where a rotor blade and a stator vane are disposed. In FIG. 8, only one side of the diffuser 100 behind the center shaft (rotary shaft) L is shown, omitting the other side thereof. The diffuser 100 is formed so as to increase gradually in cross sectional area, thereby converting dynamic pressure of fluid F discharged from the passage to static pressure. Here, the diffuser 100 is set for passage extension, curvature in passage extension direction, change rate of cross sectional area, area ratio of inlet to outlet, or the like, based on analysis according to CFD (computational fluid dynamics), or the like, and testing in such a manner that a change in cross sectional area will not cause separation to the fluid F in circulation and also will attain effective deceleration. Further, the diffuser 100 is extended along the axial direction together with a passage on the side of an inlet 100 a and curved so as to move to the side of the outer circumference in the radial direction in line with moving to the side of an outlet 100 b, thus formed in the shape of a horn as a whole. Also, an exhaust scroll 101 is arranged annularly on the side of the outer circumference of the outlet 100 b in the radial direction so as to be connected to an outlet opening 100 c of the diffuser 100, and the fluid F flows from the diffuser 100. The fluid F which has flowed into the exhaust scroll 101 swirls along an inner wall surface 101 a of the exhaust scroll 101 inside a cross section including the center shaft L and flows along the circumferential direction after mixture with the fluid F flowing at a position different in the circumferential direction.

PATENT DOCUMENT

Patent Document 1: Japanese Published Unexamined Utility Model Application No. H7-8597

Patent Document 2: Japanese Published Unexamined Patent Application No. 2005-155393

DISCLOSURE OF INVENTION Problems to be Solved by the Invention

However, in the exhaust scroll 101 with a structure described in Patent Documents 1, and 2 shown in FIG. 8, there has been a problem in that the fluid F swirling along the inner wall surface 101 a of the exhaust scroll 101 inside the cross section including the center shaft L collides and mixes with newly flowing fluid F at an inlet portion 101 b to cause pressure loss.

The present invention has been made in view of the above situation, an object of which is to provide an exhaust scroll capable of collecting and discharging fluid which has flowed into the exhaust scroll, while reducing pressure loss due to collision and mixing of fluid swirling inside the exhaust scroll with fluid flowing thereinto.

Means for Solving the Problem

The aspects of the present invention adopts the following means for solving the above problem. The first aspect of the present invention is an exhaust scroll which is connected to an exhaust passage of a turbomachinery and into which fluid discharged from the exhaust passage flows, the exhaust scroll, including: a scroll body in which a space having a substantially annular cross section is formed; and a connecting portion which connects the exhaust passage with the scroll body to forcibly decelerate the fluid discharged from the exhaust passage, thereby allowing the fluid to flow into the scroll body.

According to the above-described configuration, the fluid which has flowed from the exhaust passage into the connecting portion is to be forcibly decelerated by the connecting portion. Therefore, the fluid flows into the scroll body in a sufficiently decelerated state, thus making it possible to reduce pressure loss due to collision, mixing, and gathering of the fluid which has flowed thereinto and fluid swirling in the scroll body.

In the exhaust scroll, the connecting portion may be provided with an inlet portion connected to the exhaust passage and an outlet portion whose passage area of the fluid is expanded more than the inlet portion to decelerate fluid being circulated by expansion of the passage area.

The above configuration makes it possible to forcibly and effectively decelerate fluid flowing from the inlet portion of the connecting portion to the outlet portion thereof by expansion of the passage area.

In the exhaust scroll, the connecting portion may separate the fluid along a wall portion connecting from the inlet portion to the outlet portion.

The above configuration makes it possible to forcibly and effectively decelerate the fluid flowing from the inlet portion to the outlet portion at the connecting portion by separating the fluid along the wall portion.

In the exhaust scroll, the connecting portion may be disposed all over at the inlet portion of the wall portion or in the vicinity of the inlet portion and provided with a corner for separating the fluid, thereby separating the fluid at the outlet portion side after the fluid passing the corner.

According to the above configuration, the fluid is separated at the outlet portion side after the fluid passing the corner, which is disposed at the inlet portion of the wall portion or in the vicinity of the inlet portion. Therefore, it is possible to forcibly and effectively decelerate the fluid at the connecting portion and also to reliably prevent the fluid from being separated by the corner up to an extent to the exhaust passage side.

In the exhaust scroll, the connecting portion may be provided with a fluid separating portion for forcibly separating the fluid.

According to the above configuration, the fluid flowing in the connecting portion is forcibly separated by the fluid separating portion, by which the fluid is effectively decelerated.

The second aspect of the present invention is a turbomachinery, including: the above-mentioned exhaust scroll; and an exhaust passage for discharging the fluid into the exhaust scroll.

The above configuration is able to reduce pressure loss due to collision and mixture of fluid at the exhaust scroll and also to effectively reduce the overall loss.

Effect of the Invention

According to the exhaust scroll of an aspect of the present invention, it is possible to reduce pressure loss due to collision, mixing, and gathering of fluid swirling inside the exhaust scroll and fluid flowing thereinto in the exhaust scroll. Also it is possible to collect and discharge the fluid which has flowed thereinto.

Further, according to the turbomachinery of another aspect of the present invention, it is possible to reduce the overall loss and discharge the used fluid from the exhaust passage via the exhaust scroll.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a half cross sectional view of an axial-flow compressor of a first embodiment of the present invention.

FIG. 2 is a cross sectional view which shows the details of an exhaust scroll of the first embodiment of the present invention.

FIG. 3 is a cross sectional view which shows the details of an exhaust scroll, that is, a first modified example of the first embodiment of the present invention.

FIG. 4 is a cross sectional view which shows the details of an exhaust scroll, that is, a second modified example of the first embodiment of the present invention.

FIG. 5 is a cross sectional view which shows the details of an exhaust scroll, that is, a third modified example of the first embodiment of the present invention.

FIG. 6 is a cross sectional view which shows the details of an exhaust scroll, that is, a fourth modified example of the first embodiment of the present invention.

FIG. 7 is a cross sectional view which shows the details of an exhaust scroll of a second embodiment of the present invention.

FIG. 8 is a cross sectional view which shows a conventional exhaust scroll.

BEST MODE FOR CARRYING OUT THE INVENTION First Embodiment

A description will be given of the first embodiment of the present invention with reference to FIG. 1 and FIG. 2.

FIG. 1 shows an axial-flow compressor 1 as one example of a turbomachinery. As shown in FIG. 1, the axial-flow compressor 1 is provided with a rotor 2, a casing 3 disposed in a substantially tubular shape on an outer circumference of the rotor 2, thereby forming between itself and the rotor 2 a passage 1 a having a substantially annular cross section at which air A, that is, working fluid, flows, stator vanes 4 and rotor blades 5 disposed inside the passage 1 a, a suction scroll 6 and an exhaust scroll 10 for supplying and discharging the air A to and from the passage 1 a, a suction passage 7 and an exhaust passage 8 for connecting the suction scroll 6 and the exhaust scroll 10 with the passage 1 a.

The stator vanes 4 are mounted on an inner circumferential surface of the casing 3 and disposed on the side of the inner circumference thereof in the radial direction toward the rotor 2. Further, the rotor blades 5 are mounted on the rotor 2 and disposed so as to protrude on the side of the outer circumference thereof in the radial direction toward the casing 3. Multiple numbers of the stator vanes 4 and the rotor blades 5 are individually disposed in a radial pattern and also disposed in multiple rows alternately along an axial direction X.

The suction scroll 6 is disposed on one side of the casing 3 in the axial direction X (on the upstream side) and connected to the passage 1 a by the suction passage 7. The suction scroll 6 is provided with a space which is formed substantially in an annular shape, allowing the air A which has flowed from a suction port (not shown) to flow along a circumferential direction Y and supplying the air A via the suction passage 7 all over the passage 1 a formed so as to have a substantially annular cross section.

As shown in FIG. 2, the exhaust passage 8 is disposed on the other side of the casing 3 in the axial direction X (on the downstream side) and configured as a diffuser for decelerating the air A which is compressed and flowed inside the passage 8 by gradually increasing a flowing cross section without causing separation. Further, the exhaust passage 8 constituting the diffuser is extended together with the passage 1 a on the side of the inlet 8 a along the axial direction X, curved so as to move toward the side of the outer circumference in the radial direction along the side of the outlet 8 b, and formed as the shape of a horn as a whole. Also, the exhaust scroll 10 is arranged annularly on the side of the outer circumference of the outlet 8 b in the radial direction so as to be connected to an opening of the outlet 8 b on the exhaust passage 8.

The exhaust scroll 10 is provided with a scroll body 11 in which a space having a substantially annular cross section is formed and a connecting portion 12 for connecting the exhaust passage 8 with the scroll body 11 and allowing the air A to flow into the scroll body 11 by forcibly decelerating the air A discharged from the exhaust passage 8. When the inlet portion 12 a connected to the exhaust passage 8 is compared with the outlet portion 12 b connected to the scroll body 11 at the connecting portion 12, the outlet portion 12 b is formed larger in passage area. Further, at the connecting portion 12, the inlet portion 12 a is connected to the outlet portion 12 b by the wall portion 12 c. In the present embodiment, the connecting portion 12 has a substantially trapezoidal cross section as a whole on the cross section including the center shaft L, and a corner 13 is formed at the inlet portion 12 a between the connecting portion 12 and the exhaust passage 8. Here, a passage-area increasing amount per unit length of the connecting portion 12 along a direction at which the air A flows; that is, a passage-area increasing rate, is set to be larger than a passage-area increasing rate of the exhaust passage 8. Further, at the connecting portion 12, the passage-area increasing rate is set in such a manner that the passage area increases rapidly from the inlet portion 12 a to the outlet portion 12 b to separate the air A flowinging along the wall portion 12 c from the wall portion 12 c. In addition, at the connecting portion 12, the wall portion 12 c which connects the inlet portion 12 a with the outlet portion 12 b may be provided only on one side in the axial direction X (on the upstream side), or only on the other side in the axial direction X (on the downstream side) or on both sides, when viewed from the cross section including the center shaft L.

Further, the scroll body 11 is provided with a flow portion 14 which is connected to the side of the outer circumference of the outlet portion 12 b of the connecting portion 12 in the radial direction and a body portion 15 which is an expanding space adjacent in the axial direction X from the flow portion 14, thereby allowing the air A which has flowed thereinto to flow as flow swirling along the circumferential direction Y. As shown in FIG. 2, when the scroll body 11 is viewed from the cross section including the center shaft L, the inner wall surface 11 a constituting the scroll body 11 is formed to give a smooth curve line between the flow portion 14 and the body portion 15. Still further, the body portion 15 expands not toward the flow portion 14 but toward the inner circumference side in the radial direction. And, between the body portion 15 and the connecting portion 12, a wall body is configured as a flow restricting portion 16 for restricting the air A directly flowing from the connecting portion 12 into the body portion 15.

Next, a description will be given of actions of the exhaust scroll 10 of the present embodiment.

As shown in FIG. 2, the air A flowing from the exhaust passage 8 into the exhaust scroll 10 first flows inside the connecting portion 12. Since the connecting portion 12 is formed so as to be larger in passage area from the inlet portion 12 a to the outlet portion 12 b, the air A which has flowed into the connecting portion 12 is to be forcibly decelerated. Further, in the present embodiment, expansion of the passage area from the inlet portion 12 a to the outlet portion 12 b is rapidly changed to cause separation A1 to the air A flowing along the wall portion 12 c, thereby making it possible to attain more effective deceleration. In addition, the wall portion 12 c may be provided only on one side in the axial direction X (on the upstream side), or only on the other side in the axial direction X (on the downstream side) or on both sides, when viewed from the cross section including the center shaft L.

Further, as described above, air A2 which flows at the connecting portion 12 and flows into the flow portion 14 of the scroll body 11 further swirls inside the body portion 15 along the inner wall surface 11 a at the cross section including the center shaft L. Also, air A3 which swirls inside the body portion 15 flows along the flow restricting portion 16 to the side of the outer circumference in the radial direction, thereby the air A3 is collided and mixed with the air A2 newly flowing into the body portion 15 from the flow portion 14. However, as described above, since the air A2 which flows from the flow portion 14 into the body portion 15 is in a sufficiently decelerated state at the connecting portion 12, it is possible to reduce pressure loss due to collision, mixture and subsequent gathering the air flows in the scroll body 11.

Here, as described above, the separation A1 is caused at the connecting portion 12, resulting in pressure loss. However, it is possible to attain significant reduction in pressure loss caused by collision, mixture and subsequent gathering inside the scroll body 11 in association with deceleration at the connecting portion 12. Thereby, the pressure loss can be reduced as a whole. Therefore, by connecting the exhaust scroll 10 to the exhaust passage 8 of an efficient diffuser, which is designed not to generate separation inside, a more efficient scroll can be provided. Also, as describe above, the separation A1 is generated at the wall portion 12 c of the connecting portion 12. However, the separation A1 is generated on the side of the outlet portion 12 b viewed from the corner 13 as the reference point, since the corner 13 is formed at the inlet portion 12 a. As a result, generation of separation A1 at the upstream side of the exhaust passage 8 can be prevented. The form of the corner is not limited to the form in which the inner wall surfaces cross each other as described above. It may include forms in which a projection is formed all over at the inlet portion 12 a or in the vicinity of the inlet portion 12 a and a corner is formed by the leading end of the projection.

FIG. 3 shows a modified example of the first embodiment. As shown in FIG. 3, in the present modified example, an exhaust passage 20 is formed as a whole along the axial direction X. Also, a connecting portion 22 is also formed along the axial direction X so as to correspond to the exhaust passage 20 at an exhaust scroll 21 and connected to the exhaust passage 20. Further, at the exhaust scroll 21, a scroll body 23 is that in which a flow portion 14 is connected to the connecting portion 22 in the axial direction X and a body portion 15 expands to the side of the outer circumference of the flow portion 14 in the radial direction. As described above, also where the exhaust passage 20 is connected to the exhaust scroll 21 along the axial direction X, a similar configuration can be provided to effectively reduce pressure loss due to collision, mixture and subsequent gathering inside the scroll body 23.

FIG. 4 shows a modified example of the present embodiment. As shown in FIG. 4, in a discharge casing 30 of the present modified example, a wall portion 12 c is formed to give stages, each of which has a step 12 d, when viewed from the cross section including the center shaft L. The step 12 d functions as a fluid separating portion, thus making it possible to forcibly separate air A along the wall portion 12 c. Also, separation A4 is caused forcibly by the step 12 d to the air A along the wall portion 12 c. Thereby, the air A flowing at a connecting portion 12 can be effectively decelerated to further reduce pressure loss due to collision, mixture and subsequent gathering inside the scroll body 11. In addition, the step 12 d may be provided only on one side in the axial direction X (on the upstream side), or only on the other side in the axial direction X (on the downstream side) or on both sides, when viewed from the cross section including the center shaft L.

FIG. 5 shows a third modified example of the present embodiment. As shown in FIG. 5, an exhaust scroll 40 of the present modified example is that in which a wall portion 41 a of a connecting portion 41 is formed on one side in the axial direction X (on the upstream side), when viewed from the cross section including the center shaft L. That is, the connecting portion 41 is rapidly expanded in passage cross sectional area on the internal side thereof where air A turns. Further, in the present modified example, a body portion 43 is formed at a scroll body 42 so as to expand not at the connecting portion 41 but on the side of the outer circumference in the radial direction. The body portion 43 is configured in such a manner as to be free of the flow restricting portion 16 shown in FIG. 2. The connecting portion 41 of the present modified example is able to cause separation A5 to the air A along the wall portion 41 a. And, the thus caused separation A5 is able to effectively decelerate the air A flowing at the connecting portion 41. Thereby, even when the exhaust scroll 40 is configured in such a manner that air A3 swirling inside the scroll body 42 flows toward the flow portion 14, with the flow restricting portion 16 not being disposed, it is possible to reduce pressure loss due to collision, mixture and subsequent gathering of the air A3. In addition, the wall portion 41 a may be provided on the other side in the axial direction X (on the downstream side) or on both sides.

FIG. 6 shows the fourth modified example of the present embodiment. As shown in FIG. 6, an exhaust scroll 50 of the present modified example is that in which a plurality of middle walls 51, each of which has a substantially triangular cross section at which the side of an inlet portion 12 a is given as a top 51 a and the side of an outlet portion 12 b is given as a bottom, are supported by a column support 52 and formed inside the connecting portion 12 as fluid separating portions. And, air A which has flowed from the inlet portion 12 a flows between the middle walls 51 and also between the middle wall 51 and the wall portion 12 c, thus causing separation A6, with a corner 51 b on the bottom side of each middle wall 51 given as a starting point. Therefore, the air A flowing at the connecting portion 12 is decelerated more effectively by the separation A6 on the middle walls 51. It is, thereby, possible to reduce more effectively pressure loss due to collision, mixture and subsequent gathering inside the scroll body 11.

Second Embodiment

Next, a description will be made for the second embodiment of the present invention. FIG. 7 shows the second embodiment of the present invention. In the present embodiment, members commonly used in the previously described embodiments are given the same reference numerals, with the description omitted here.

As shown in FIG. 7, at a connecting portion 62 of an exhaust scroll 61, a portion inside the passage thereof is formed not to give a smooth curved line but to give a corner 61 a. Further, in the present embodiment, at a position which is inside the passage of the connecting portion 62, a corner 61 b is formed at a connecting portion of a body portion 15 with the connecting portion 62.

In the exhaust scroll 61 of the present embodiment, when air A flowing through the exhaust passage 60 flows into the connecting portion 62, the corner 61 a functions as a forced separating portion due to the fact that the corner 61 a is formed at a position which is inside the passage, thereby causing separation A7 to the flow of air A. Similarly, when air A3 which flows from the connecting portion 62 into a scroll body 63 to swirl inside the body portion 15 flows along the flow restricting portion 16 to the side of the outer circumference in the radial direction, the corner 61 b functions as a forced separating portion, thus causing separation A8 to the flow of air A3. Therefore, the air A flowing in the connecting portion 62 and the air A3 flowing in the body portion 15 are disturbed by the separations A7, A8 to cause pressure loss and rapidly decelerated. Thus, even with collision and mixing of the air A flowing in the connecting portion 62 with the air A3 flowing in the body portion 15, it is possible to reduce pressure loss accordingly and reduce the pressure loss as a whole. Further, the air A which flows from the connecting portion 62 into the scroll body 63 flows substantially in the same direction as the air A3. It is, thereby, also possible to suppress the occurrence of pressure loss on mixture.

A description has been made so far in detail for the embodiments of the present invention with reference to the drawings. Specific configurations will not be limited to these embodiments, and the present invention includes modifications of design, or the like, in a scope not departing from the gist of the present invention.

A description has been made for the exhaust scrolls shown in the above-described respective embodiments and modified examples as those to be mounted on an axial-flow compressor. However, the present invention shall not be limited thereto but applicable to a centrifugal compressor. Further, the present invention shall not be limited to a compressor but also applicable to a structure capable of discharging working fluid in various turbomachineries such as a gas turbine, a steam turbine and a submergible pump.

INDUSTRIAL APPLICABILITY

According to the exhaust scroll of the present invention, fluid which has flowed from the exhaust passage into the connecting portion is forcibly decelerated by the connecting portion. The fluid which has been sufficiently decelerated and flowed into the scroll body is subjected to collision and mixture with fluid swirling at the scroll body and subsequently subjected to concentration at the scroll body, thus making it possible to reduce pressure loss.

DESCRIPTION OF REFERENCE NUMERALS

-   1: Axial-flow compressor (Turbomachinery) -   8, 20, 60: Exhaust passage -   10, 21, 30, 40, 50, 61: Exhaust scroll -   11, 42, 63: Scroll body -   12, 22, 41, 62: Connecting portion -   12 a: Inlet portion -   12 b: Outlet portion -   12 c: Wall portion -   12 d: Step (Forced separating portion) -   13: Corner -   51 b: Corner (Forced separating portion) -   61 a, 61 b: Corner (Forced separating portion) -   A: Air (Fluid) 

1. An exhaust scroll which is connected to an exhaust passage of a turbomachinery and into which fluid discharged from the exhaust passage flows, the exhaust scroll comprising: a scroll body in which a space having a substantially annular cross section is formed; and a connecting portion which connects the exhaust passage with the scroll body to forcibly decelerate the fluid discharged from the exhaust passage, thereby allowing the fluid to flow into the scroll body.
 2. The exhaust scroll according to claim 1, wherein the connecting portion is provided with an inlet portion connected to the exhaust passage and an outlet portion whose passage area of the fluid is expanded more than the inlet portion to decelerate fluid being flowed by expansion of the passage area.
 3. The exhaust scroll according to claim 2, wherein the connecting portion separates the fluid along a wall portion connecting from the inlet portion to the outlet portion.
 4. The exhaust scroll according to claim 3, wherein the connecting portion is disposed all over at the inlet portion of the wall portion or in the vicinity of the inlet portion and provided with a corner for separating the fluid, thereby separating the fluid at the outlet portion side after the fluid passing the corner.
 5. The exhaust scroll according to claim 1, wherein the connecting portion is provided with a fluid separating portion for forcibly separating the fluid.
 6. A turbomachinery, comprising: the exhaust scroll according to claim 1; and an exhaust passage for discharging the fluid into the exhaust scroll.
 7. The exhaust scroll according to claim 2, wherein the connecting portion is provided with a fluid separating portion for forcibly separating the fluid.
 8. The exhaust scroll according to claim 3, wherein the connecting portion is provided with a fluid separating portion for forcibly separating the fluid.
 9. The exhaust scroll according to claim 4, wherein the connecting portion is provided with a fluid separating portion for forcibly separating the fluid.
 10. The turbomachinery, comprising: the exhaust scroll according to claim 2; and an exhaust passage for discharging the fluid into the exhaust scroll.
 11. The turbomachinery, comprising: the exhaust scroll according to claim 3; and an exhaust passage for discharging the fluid into the exhaust scroll.
 12. The turbomachinery, comprising: the exhaust scroll according to claim 4; and an exhaust passage for discharging the fluid into the exhaust scroll.
 13. The turbomachinery, comprising: the exhaust scroll according to claim 5; and an exhaust passage for discharging the fluid into the exhaust scroll. 